This invention relates to a triangulated cable dome which supports a roof for an underlying building, arena or stadium and which is provided with a retractable roof section. More particularly, it relates to a cable dome formed of a plurality of tension members and compression members arranged in a triangulated manner for supporting a roof, and a retractable roof for the cable dome.
In the modern era of sports and entertainment, domed stadiums have become the vogue. Starting in the 1960s and 1970s, several domed multipurpose stadiums were built. These stadiums were designed to eliminate weather as a factor in sporting and entertainment events, thereby increasing stadium use and revenue. In my co-pending parent application, Ser. No. 07/608,497 filed Nov. 2, 1990, I described some of the many mechanical and structural shortcomings of these early domed structures. While some domed structures, namely those of the type described in U.S. Pat. No. 3,139,957 to Fuller and U.S. Pat. No. 4,736,553 to Geiger, overcome some of the shortcomings of the earlier designs by using the principles of catenary suspension, these structures had limited application to non-circular areas.
Recently, there has been a demand for arenas or stadiums having a roof or a portion of a roof that may be opened or closed depending on the weather. When closed, the roof keeps out inclement weather thereby protecting the floor or field of the arena and the spectators so that the event may be held. Conversely, when the weather is favorable, the roof may be opened to allow the spectators to enjoy the weather as well as the event. Such a stadium is particularly desirable where a natural playing surface, such as grass, is used, since natural grass cannot be easily grown indoors. Until now, sports, such as soccer, which are preferably played on natural grass, have been played outdoors and are therefore subject to the forces of nature. A domed stadium with a retractable roof or roof section allows grass to be grown thereby allowing these sports to be played indoors on a grass field. Accordingly, a domed stadium that has a portion or section of roof that is retractable is desired. Such a stadium provides protection to the fans, the players and the playing surface during inclement weather but also allows the fans and players to enjoy fair weather. Moreover, the roof allows for the use of natural grass in a dome enclosed arena.
One retractable domed stadium is illustrated in U.S. Pat. Nos. 4,676,033 and 4,716,691 to Allen et al. which describe the recently constructed Sky-Dome in Toronto, Canada. These patents illustrate a stadium that is circular in plan and has two parallel, rectangular wings running along opposite sides of the circular stadium. The domed roof of the stadium includes four arched roof panels; a fixed ungular end segment, a movable ungular end segment that rotates on a circular track into a nesting relationship with the fixed end segment and a pair of central arches which are movable to rest above the nesting end segments.
Significantly, this retractable roof is constructed of rigid structural members and suffers from numerous shortcomings. First, the use of rigid structural members is inefficient, resulting in a roof structure that is extraordinarily heavy and complicated. Second, due to the weight and complex movements of the individual roof panels, the roof is slow to open or close, thereby subjecting the stadium occupants to dangerous conditions should the weather change quickly. Third, the complex nature and movements of the movable panels leads to a stadium that is costly to construct and to maintain.
In light of these shortcomings, it is desirable to provide a domed stadium having a retractable roof section which is lightweight, inexpensive to build and maintain, and simple to construct and operate.